Bag packer



BAG PACKER '3 Sheets-Sheet 1 Filed Feb. 11, 1957 INVENTOR.

EDW/N J. DOUGLAS .4 TTORNEYS March 18, 1958 E. J. DOUGLAS 7 2,827,256

BAG PACKER Filed Feb. 11, 1957 3 Sheets-Sheet 2 INVENTOR. EDWIN J.DOUGLAS A TTORNE S United States Patent BAG PACKER Edwin J. Douglas,Whittier, Calif., assignor to L. Stoker Company, Claremont, Calif., acorporation of California Application February 11, 1957, Serial No.639,495

14 Claims. (Cl. 249-62) This invention relates to packaging equipmentand, more particularly, is concerned with a packer for filling bags withsolid materials capable of being packaged in bags or sacks.

The packaging of all types of finely divided solid materials, such ascement, sand, grain, chemicals, plastics, and the like, in paper bags ofall sizes is well known. Various automatic machinery has been developedin the past for automatically filling bags with a predetermined quantityof material, based on the weight of the material. In an effort todecrease costs, such packaging machines have been continuously improvedin their performance to obtain faster filling rates for the bags.However, where the material is caused to flow into the bags at everfaster rates, it becomes more difiicult to ascertain theend point whenthe precise weight of material has been delivered to the bag so as tocut off the flow of material into the bag at the correct moment. Forexample, if material is fed into the bag out of a spout, and the flowout of the spout is to be interrupted when the weight of the bag withthe material in it reaches a predetermined level, inaccuracies can existbecause at any given moment a quantity of material necessarily haspassed the point at which the flow is interrupted and yet has not cometo rest in the bag where its weight can be measured. The faster the rateof feed, the greater error is introduced between the measuring of theweight, interruption of the llow, and the amount of material being addedto the weight of the bag after the interruption of the flow of materialis effected. As the cost of the material being packaged goes up, theadditional ounces or even pounds of material, added to the bags weightafter a weight measurement has resulted in the interruption of flow ofmaterial into the bag, become more and more of an economic factor in theover-all cost of the packaged item.

The present invention provides bag-packing equipment which is capable offilling bags at a very high rate and yet maintaining high weightaccuracies that are reproduceable from bag to bag. The present inventiontherefore has particular utility where packaging of bulk materials inbags must be done with extreme accuracy to prevent waste by way ofoverweight of the filled bag. This is accomplished in the presentinvention by a bagpacker that has a two-speed drive arrangement by meansof which the material can be fed into the bag-at a high rate of speeduntil the bag is substantially filled, and at a very slow dribble speedto complete to a high degree of accuracy the filling of the bag. Aunique weightsensing arrangement senses two weight end points in thefilling of the bag. Control means actuated at each of -'-t-he's'e twoend points successively reduces the speed of main frame 10 'of themachine.

Fig. 2 is a fragmentary view showing the novel scale beam arrangementfor automatically weighing the material that goes into the bag;

Fig. 3 is a fragmentary view showing one of the pivots for the scalebeam;

Fig. 4 is an end view of the pivot of Fig. 3;

Fig. 5 is a fragmentary view of the pivot assembly for supporting themain scale beam from the frame; and

Fig. 6 is a schematic wiring diagram of the control circuit for themotor drive.

Referring in detail to the drawings, and in particular to Fig. 1, thenumeral 10 indicates generally the main frame of the bag packingmachine. The main frame includes four vertical legs 12, the foremost onein the figure being cut away to reveal details of other parts of themachine. The upper part of the frame 10 includes a pair of parallel siderails 14 which support a hopper 16 by means of suitable brackets 18.

A screw conveyor communicates with the bottom of the hopper 16, theconveyor including a screw feed shaft 20 extending from within thehopper through a tube 22 joined at one end to the hopper and out througha bag feeding spout 24. The shaft 20 is driven from a motor driveassembly indicated-generally at 26, mounted on the bottom part of themain frame 10, by means of a suitable belt drive 28, the belt driverotating a belt sheave 30 mounted on an extension of the feed shaft 20which projects out of the back of the hopper. It will be understood thatsuitable bearings are provided for rotatably supporting the feed shaft20. The drive assembly 26 includes a main drive motor 27 and a smallerdribble feed motor 29. The motor 29 is coupled to the shaft of the motor27 through a gear speed reducer 31 bag of the well known flap or valvetype. The upper end of the bag is slipped over the spout 24 and clampedin position by a suitable clamping lever assembly indicated generally at32.

The spout 24 and the clamping assembly 32 are both secured by suitablemeans to a vertical front plate 34 which extends downwardly tosubstantially the bottom of the main frame 10. A lower bag supportassembly 36 is adiustably secured to the lower end of the plate 34, alongitudinal slot 38 being provided in the plate 34 to permit adjustmentof the vertical height of the lower bag assembly 36.

In order to weigh the bag and material as the bag is filled by the screwfeed from material stored in the hopper 16 through the spout 24, theplate 34 is made part of a beam scale assembly which includes a mainscale beam 38. The main scale beam includes, at one end thereof, a pairof spaced parallel plates 40 (see Fig. 5). The parallel plates aresecured at their lower ends to a horizontal member 42, a pair ofsubstantially triangular plates 44 being provided to stiffen the weldedassembly of the parallel vertical plates 48 with the horizontal member42.

The entire main beam 38 is pivotally supported on the To this end a pairof parallel plates 46 are supported by the main frame below the hopperand are positioned on either side of the screw feed conveyor. An endplate 48 extends'between and is welded in position to the outwardlyprojecting ends of the plates 46, the end plate 48 providing a supportfor the outer end of the conveyor tube 22, as best shown in Fig. 5.

The two pivot assemblies between the "plates 46 forming part of the mainframe 10 and the'parallel plates 40 of the main scale beam are bestshown in' Figs. 3 and 4. Each of the pivot assemblies includes a block5G welded or otherwise secured to the plate 46 of the main frame. Blocks50 have a vertical hole 52 therein,

which receives a shaft 54 that is integrally formed with the knife-edgeblock 56. Similarly, blocks 60' are welded or otherwise secured to theparallel plates 40 of the main scale beam 38. The blocks 69 are providedwith axiallyaligned h0les62, which receive knife-edge pivot shafts 64.The shafts 64 are provided with 90 V- shaped slots which are milledtherein for receiving the knife-edges 56. Both the knife-edges 56 andthe coopcrating shafts 64 are made of hardened steel to reduce frictionand wear of the pivots.

The pivot assembly is self-aligning and extremely ac-I' curate. Bymachining the holes 62 through the blocks 60 after theblocks are securedto the plates 49 of the main beam assembly. 38, axial alignment of theholes is assured. The knife edges, because they are permitted to pivotor turn about a vertical axis, automatically align themselves with thegrooves in the pivot shafts 64, which grooves are accurately machined sothat the bottom of the V lies along the longitudinal axis of the shaft64.

The vertical front plate 34 from which the bag is sup- 7 ported, in turnis pivotally supported from the main scale beam 38. The pivotal supportassembly is identical to that which supports the main beam 38 from themain frame 10, as above described. Thus the plate 34 is pro- 64 mountedon the blocks 60, cooperate to pivotly support the front plate 34 fromthe main scale beam 38.

It should be noted that a flexible sleeve forms the conduitconnection inthe feed conveyor assembly between the tube 22 and the spout 24. Theflexible sleeve is necessary since, the spout 24 is subject to slightvertical motion with tilting of the main beam 38. Since the screw feedshaft 20 is vertically fixed with relation to the main frame 10,sufiicient clearance must be provided between the inside of the spout 24and the screw feed shaft 20 to permit the required vertical movement ofthe plate 34 as the main beam is tilted during the weighing operation.

In order to maintain the front plate 34 in a substantially verticalposition and still permit up and down movement thereof, the lower end ofthe plate 34 is anchored to the main frame by a pair of parallelsubstantially-horizontal rods 74 which are pivotally'secured at theirrespective ends to the main frame 10 and to the lower end of the plate34. It will be seen that the rods 74 permit slight vertical movement ofplate 34 and yet secure the plate 34 against rotation about the upperpivotal supports.

Automatic control of the feeding of material from the hopper 16 into thebag to a desired weight is controlled shaft 88 journaled in suitablebrackets 90 supported from the main scale beam. The shaft 88 is rotatedby means of a crank handle 92 which is accessible through an opening 94in the front vertical plate 34. The outer end of the horizontal member42 of the main scale beam 38 is permitted to swing between two limitstops, a lower stop 96 and an upper stop 93. A dash pot 100'm0unted onthe scale beam 38 has its plunger 102 secured to the main frame. Thedash pot clamps the movement of the main scale beam 38 between thelimits of the stops 96 and 98.

A mechanical anticipator arrangement is provided in the form of anauxiliary scale beam 101 which is pivotly supported from the main scalebeam 38 by means of a bracket 103. The auxiliary beam 101 rests on astop 164 that is secured in fixed relationship with the main frame 11 ofthe machine. An adjustable weight 106 urges the auxiliary beam againstthe stop 104. As the main scale beam 38 begins to rise, the auxiliaryscale beam pivots about the stop 104, causing the opposite end of theauxiliary scale beam to rise. As it rises, it engages an adjustable stop108 which is secured to the main scale beam 38.

When the auxiliary scale beam engages the stop 108 it causes theopposite end of the auxiliary scale beam to lift off the stop 104. Theresult is to add an additional weight to the end of the main scale beam,namely, the weight otherwise carried by the stop 104. It will be seenthat as the weight of the bag and its contents increases a point will bereached where the main scale beam is lifted ed the stop 96 causing theauxiliary scale beam 191 to engage the stop 108. The main scale beamwill then come to rest, its upward movement being halted untilsufficient additional weight has been added to the bag and its contentsto overcome the weight of the auxiliary beam to lift it ofi the stop104. Thus movement of the main scale beam 38 between stops 96 and 98takes place in two distinct steps. The microswitches 76 and '78 arearranged so that they are respectively actuated during the successivestep movements upward of the main scale beam 38.

Control of the filling of the bag by the drive assembly 26 inoperationrof the screw feed conveyor is efiected by the circuit shown inFig. 6. The main motor 27 is controlled by a multiple switch relayindicated generally at 105. The relay coil 107 of the relay has one sidethereof connected through line L to one side of a source of electricalenergy (not shown). The other side of the coil 102 is connected to onepole of a normally open pushbutton type double-pole single-throw switch199. Momentary closing of the switch 109 to start the main motorcompletes a circuit from the coil 1B7 tothe line L connected to theother side of the electrical energy source. This circuit is completedthrough a normally closed pushbutton type of single-pole single-throwswitch 111, which when momentarily opened, stops the operation of thebag packer.

Energization of the relay 107 closes three normally open switches 110,112, and 113. Switches 113 and 110 connect the main motor 27 across thelines L and L for energizing'the motor. This starts the feed conveyormechanism filling the bag in the manner above described,

supported from the main frame 10 by suitable brackets counterbalancingweight 86 which threadedly engages a F the feed mechanism being shown inFig. 6 as a block 114. The closing of switch 112 of the relay 105provides an electrical path which bypasses the start switch 109. Inorder that the main motor 27 may be stopped when the bag issubstantially filled, the bypass circuit includes the switch 112connected in'series with the main feed microswitch 76 which is opened bythe initial movement of the main scale beam 28 when the bag being filledreaches a predetermined weight.

The dribble motor 29 is controlled by a reversing relay indicatedgenerally at 116 which includes two coils 118 and 120 that actuate apair of switches 122 and 124 for reversing the connection between thedribble motor 29 and the lines L and Lg. The forward can 118 ieconnected across the lines L and Lgthr'ough the start 'sWiteh 109 andstop switch 111 in a manner similar route relay coil 107 of the mainmotor eontfol relay 105. Once the pushbutton switch 109 is closed to'energize the relay coils 107 and 118, the coil 118 is held energized bya Circuit including a switch 126 elosed by the relay coil 118 and thedribble feed microswitch 78 connected in series as shown.

Although the start switch 109 energizes the main motor 27 and also thedribble motor 29 in its forward direction, the magnetic clutch 33, whichcouples the dribble motor through the gear box 31 to the shaft of themain motor 27, is not energized. The clutch is controlled by a normallyclosed switch 128 which is part of the relay 105 and actuated by therelaycoil 107. With the relay coil 107 energized, the switch 128, whichis in'series with the magnetic clutch 33, is opened, therebyde-energizing the magnetic clutch 33 during the time the main motor 27is driving the feed mechanism 114. I

When the 'bag is filled to the point-that the main feed microswitch 76is open, the switch 128 again returns to its normally closed conditionon the de-energization of the relay coil 107. This connects the magneticclutch 33 across the lines L and L throu'gha timer-actuated switch 130in series with the switch 128. Switch 130 is actuated by a timing deviceindicated generally at 132, which includes a solenoid 134 actuating aplunger 136. The solenoid 134 is connected in parallel with the relaycoil 118 such that the switch 130 is closed whenever the dribble motor29 is energized in its forward direction.

With the magnetic clutch 33 energized, and the main motor 27de-energ'ized, the dribble motor 29 continues to fill the bag throughthe feed mechanism 114 at a greatly reduced rate. This continues untilthe weight of the bag is sufiicient to lift the auxiliary scale beam 101off the stop 104. The main scale beam 28 then lifts sutficiently toactuate the dribble feed microswitc'h 78, thereby breaking the circuitthrough the relay coil 118 and the solenoid 134 of the timer switch 132.

At this time the reverse coil 120 of the relay 116 is energized. This iseffected by a relay indicated generally at 137 which has its coil 138connected in parallel with the forward coil 118 of the relay 116. Therelay 136 includes a normally closed switch 140 connected in series withthe reverse coil 120. The circuit connecting the coil 129 across theinput lines L and L is completed by the switch 130 actuated by the timer132. When the dribble feed switch 78 is open, thereby de-energizing thesolenoid 134 of the timer 132 the plunger 136 starts to drop but isslowed down in its descent by a piston 142 moving in a cylinder 144. 7Such type of pneumatic timer devices are well known and include valvemeans such as indicated at 146 in the end of the cylinder forcontrolling the rate at which air escapes, thereby controlling the rateat which the plunger 136 and associated piston 146 drop. When theplunger 136 is fully' descended, it opens the switch 130 therebyde-energizing the reverse coil 120 to stop the reverse motion of dribblemotor 29. This completes the bag-fiiling cycle of operation, whichincludes filling the bag substantially full at a high rate of deliveryof the material being packed, bringing the bag to its full weight bydribbling in additional material at a relatively slow delivery rate, andreversing and stopping the feed when the bag has reached its fullweight. Reversing of the dribble motor insures that no additionalmaterial can reach the bag after full weight is reached.

From the above description, it will be recognized that an improved bagpacker apparatus is provided. The double beam weighing arrangementprovides positive twostep action of the main feed microswitch followedby the dribble feed microswitch, which act to control the feed drive. Bythe two speed feed arrangement, greatly increased accuracies in bagfilling are possible without sacrifice of over-all speed.

Whatis claimed isE 1. An automatic bag packer comprising a main frame, amains'eale beam pivotally mounted on the frame, means forpivotallysupporting from one end of the main scale beam the bagto be packed, afirst stop mounted on the frame for supporting the end of the scale beamopposite from the bag supporting means, means mounted on the frame forfeeding material into the bag, reversible twospeed motor drive means foractuating the feeding means to control the rate of feed, an auxiliaryscale beam pivotally supported from the main scale beam at the oppositeend thereof from the bag supporting means, a second stop mounted on theframe for supporting one end of the auxiliary 'beam, a limit stopmounted on the main scale beam'forlimiting rotation of the auxiliarybeam about the pivotal support thereof as the main beam rises due toincreasing weight of the bag as it is being packed, whereby theauxiliary beam is lifted otf the second stop on the frame after'the mainbeam rises a predetermined amount above the first stop, a first switchmeans actuated by the pivotal movement of the main beam off the firststop, second switch means actuated by the further movement of the mainbeam when the auxiliary beam lifts off the second stop, means responsiveto actuation of the first switch means for reducing the speed of themotor drive means, means responsive to actuation of the second switchmeans for reversing the motor drive means, and time controlled means forstopping the drive means a predetermined time after the second switchingmeans is actuated.

2. Apparatus as defined in claim 1 wherein the twospeed drive meanscomprises first and second motors, a speed-reducing gear drive connectedto the second motor, and an electrically controlled magnetic clutchcoupling the first motor to the output of the gear drive, the firstmotorbeing connected to the feeding means.

3. Apparatus as defined in claim 2 wherein the first switch means whenactuated cuts off power to the first motor and engages the clutch, andthe second switch means when actuated reverses the second motor to backoff the feed and stop further filling of the bag.

4. An automatic bag packer comprising a main frame, a main scale beampivotally mounted on the frame, means for pivotally supporting from oneend of the main scale beam the bag to be packed, a first stop mounted onthe frame for supporting the end of the scale beam opposite from the bagsupporting means, means mounted on the frame for feeding material intothe bag, two-speed motor drive means for actuating the feeding means tocontrol the rate of feed, an auxiliary scale beam pivotally supportedfrom the main scale beam at the opposite end thereof from the bagsupporting means, a second stop mounted on the frame for supporting oneend of the auxiliary beam, a limit stop mounted on the main scale beamfor limiting rotation of the auxiliary beam about the pivotal supportthereof as the main beam rises due to increasing weight of the bag as itis being packed, whereby the auxiliary beam is lifted off the secondstop on the frame after the main beam rises a predetermined amount abovethe first stop, a first switch means actuated by the pivotal movement ofthe main beam off the first stop, second switch means actuated by thefurther movement of the main beam when the auxiliary beam lifts off thesecond stop, means responsive to actuation of the first switch means forreducing the speed of the motor drive means, means responsive toactuation of the second switch means for stopping the drive means.

5. An automatic bag packer comprising a main frame, a main scale beampivotally mounted on the frame, means for pivotally supporting from oneend of the main scale beam the bag to be packed, a first stop mounted onthe frame for supporting the end of the scale beam opposite from the bagsupporting means, means mounted on the frame for feeding material intothe bag, two-speed motor drive means for actuating the feeding means tocontrol the rate of feed, an auxiliary scale beam, a secof the auxiliarybeam, means mounted on the main scale beam for picking up the auxiliarybeam off the second stop when the main beam has moved a predeterminedamount as the main beam rises due to increasing weight of the bag as itis being packed, a first switch means actuated by the pivotal movementof the main beam off the first stop, second switch means actuated by thefurther movement of the main beam when the auxiliary beam lifts off thesecond stop, means responsive to actuation of the first switch means forreducing the speed of the motor drive means, means responsive toactuation of the second switch means for stopping the drive means.

6. Apparatus as defined in claim wherein, the two speed drive meanscomprises first and second motors, a speed-reducing gear drive connectedto the second motor, and an electrically controlled magnetic clutchcoupling the first motor to the output of the gear drive, the firstmotor being connected to the feeding means.

7. Apparatus as defined in claim 6 wherein the first switch means whenactuated cuts off power to the first motor and engages the clutch, andthe second switch means when actuated reverses the second motor to backoff the feed and stop further filling of the bag.

8. A bag packer comprising a main frame, a scale beam pivotally mountedon the frame, means for pivotally supporting a bag to be packed from oneend of the scale a beam, means for feeding material into the bag when itis in position on the supporting means, two-speed drive means foractuating the feeding means at one of two selectable rates, means fornormally maintaining the scale beam substantially horizontal until theWeight of the bag and material therein exceeds a predetermined value,means for abruptly increasing the counterbalancing weight of the scalebeam when the beam rotates a predetermined amount due to the weight ofthe bag and material feed thereto, means for actuating the two-speeddrive means to reduce the feed rate to a lower value in response to theinitial rotational movement of the beam about its pivotal support, meansfor interrupting the feed by said material feeding means when the scalebeam is caused to rotate further against the abruptly added additionalcounterbalancing weight.

9. Apparatus as defined in claim 8 wherein said means for pivotallysupporting the scale beam from the main frame includes a pair of knifeedge members supported in spaced relationship from the frame with theirknife edges projecting upwards and lying in a common horizontal plane,each of the knife edge members being rotatable about a vertical axis,whereby the knife edges can be adjusted for exact alignment with eachother, and a pair of shaft members supported in spaced relationship fromthe scale beam, the shaft members being rotatable about a common axisand having longitudinally extending V-shaped grooves therein, the bottomof the grooves lying along said common axis, whereby rotation of theshaft members does not aifect the location of the bottom of the grooves,the knife edge members engaging the grooves in the shaft members forsupporting the scale beam.

10. Apparatus as defined in claim 8 wherein the twospeed drive meanscomprises first and second motors, a speed-reducing gear drive connectedto the second motor, and an electrically controlled magnetic clutchcoupling the first motor to the output of the gear drive, the firstmotor being connected to the feeding means.

'11; Apparatus as defined in claim 10 wherein the first switch meanswhen actuated cuts off power to the first motor and engages the clutch,and the second switch means when actuated'reverses the second motor toback off the feed and stop further filling of the bag.

12. in an automatic bag packer having means for feeding the materialinto the bag and means for sensing the weight of the bag and material attwo separate and distinct values, a two-speed feed drive comprising afirst motor having its drive shaft connected to the feeding means, asecond motor, speed-reducer means connected to the drive shaft of thesecond motor, a magnetic clutch coupling the drive shaft of the firstmotor to the output shaft of the speed-reducer means, and electricalcontrol means for the two motors and the clutch responsive to saidweight sensing means, the control means including means forde-energizing the first motor and energizing the clutch when the weightof the bag and material therein reaches the first of said two values,and means for reversing momentarily and then tie-energizing the secondmotor when the weight of the bag and material therein reaches the secondof said two values.

13. In an automatic bag packer having means for feeding the materialinto the bag and means for sensing the weight of the bag and material attwo separate and distinct values, a two-speed feed drive comprising afirst motor having its drive shaft connected to the feeding means, asecond motor, speed-reducer means connected to the drive shaft of thesecond motor, a magnetic clutch coupling the drive shaft of the firstmotor to the output shaft of the speed-reducer means, and electricalcontrol means for the two motors and the clutch responsive to saidweight sensing means, the control means including means forde-energizing the first motor and energizing the clutch when the weightof the bag and material therein reaches the first of said two values,and means for interrupting the feed by the drive means when the Weightof the bag and material therein reaches the second of said two values.

14. In a bag packing device in which the eeding spout supports the bagfrom a scale beam, pivotal means for supporting the scale beam andassociated spout and bag from a main frame of the device comprising apair of knife edge members supported in spaced relationship from theframe with their knife edges projecting upwards and lying in a commonhorizontal plane, each of the knife edge members being rotatable about avertical axis, whereby the knife edges can be adjusted for exactalignment with each other, and a pair of shaft members supported inspaced relationship from the scale beam, the shaft members beingrotatable about a common axis and having longitudinally extendingV-shaped grooves therein, the bottom of the grooves lying along saidcommon axis, whereby rotation of the shaft members does not affect thelocation of the bottom of the grooves, the knife edge members engagingthe grooves in the shaft members for supporting the scale beam.

Hartley Sept. 3, 1889 2,613,053 Dorrington Oct. 7, 1952 2,794,613 OwenJune 4, 1957

